Wireless charging is an evolving technology that may bring a new level of convenience of charging electronic devices. In a wireless charging system, particularly an inductive wireless charging system, energy is transferred from one or more power transmitter (TX) coils to one or more power receiver (RX) coils through a coupling of a magnetic field.
A magnetic coil can generate a magnetic field, and the coupling of the magnetic field between TX and RX coils is influenced by the alignment of the coils. A good alignment generally leads to a good coupling, which is critical to a high-efficient power transfer. When there is an offset in the alignment, the coupling may be negatively affected. A magnetic coil with a high uniformity of magnetic field may overcome the negative effect brought by the offset, and maintain a good coupling between the TX and RX coils, thus, maintain a high-efficient power transfer.
To improve user experiences and increase the charging efficiency, it is desirable to have a magnetic coil with a high magnetic field uniformity, so that users can leave one or more RX devices freely on the TX surface in any location or direction to charge. This disclosure proposes a method and system for evaluating the magnetic field uniformity of a magnetic coil in a wireless charging system.